As drug maker Allergan Inc. tries to avoid being acquired, it is taking a page from its pursuer, Valeant Pharmaceuticals International Inc.

The Botox maker said Monday it is laying off workers and cutting drug research—exactly what Valeant said it would do if it acquired Allergan—as it tries to convince investors it's capable alone of delivering strong earnings growth. The layoffs will represent 13% of Allergan's workforce, the...